Apparatus for converting higher boiling hydrocarbons into lower hydrocarbons



Jan. 12, 1937. c, p u s 2,067,832

' APPARATUS FOR CONVERTING HIGHER BOILING HYDROCARBONS INTO LOWERHYDROCARBONS Original Filed Sept. 12, 1929 Z r fiz eflto r 3 117266Carbon r-Dubbs Patented Jan. 12, 193? PATENT OFFICE APPARATUS FORCONVERTING HIGHER BOILING HYDBOCARBONS INTO LOWER HYDROCABBONS Carbon P.Dnbbs, Chicago, IlL, anlgnor, by memo assignments, to Universal OilProducts Com-- pany, Chicago, Ill., a corporation of DelawareApplication September re, 1929. Serial No. scam Renewed October 8, 19852 Claims. (or. 196-101).

In converting higher to lower boiling oils having anti-knock properties,I find it is 0! great advantage for said oil to be brought to itsmaximum allowable temperature in the shortest possible time, thismaximum allowable temperature ranging from approximately 800 to 1100degrees F. I give a range of temperature rather than a specifictemperature, because in the operation of my apparatus the temperaturesused will be governed by the oil being treated and the products desiredand qualities sought; in fact, the maximum allowable temperature shouldbe just below that temperature at which it is physically impossible todissipate the heat before the speed of the reaction converts anundesirable amount of the oil into fixed gas and'coke. While the oil isin the heating and reaction elements, theoil should be held undersufficient pressure so that vaporization will not proceed to that degreewhere coke is formed.

I find that the higher temperatures increase the anti-knock propertiesof the desired low boiling point products. Such liquid residue as onechooses to make is practically tree from coke and sludge. Furthermore,by the control of the operation, the residue can be made to have anydesired viscosity, within wide limits. On the other hand, operations,wherein all of the volatile part of the oil is vaporized, result in amore complete breaking up of the oil which produce a higher carbon cokeand, therefore, lesser volume of coke residue. The results arevdependent upon bringing the .oil quickly to the desired temperature,maintaining the oils at that temperature not longer than the timenecessary to eflect, the desired reaction, then quickly reducing suchtemperatureto such degree as to produce the desired result, separatingthe residual liquid or coke vfrom the vapors, reducing the temperatureof such vapors, to separate the higher boiling point vapors from thelower boiling point vapors, .by condensing the former and againsubjecting them to another like treatment, along with a fresh supply ofraw oil. The lower boiling point vapors are condensed and arewithdrawnin whole or in part, from the process. The higher the temperature towhich the oil is heated, the shorter the time such oil must be subjectedto such temperature. This rule-holds true until temperatures are reachedat which the speed of the reaction is so great as to produce anundesirable volume oi-ilxed'gas or coke before the reaction can bearrested by cooling. In the use or these high temperatures, it is veryessential that the oil be reduced in temperature 'coke or sludge.

in the quickest way so as to positively control the quality oi. theproducts desired. The appa ratus I have shown in the accompanyin drawingis suitably adapted to accomplish these results.

The volumetric ratio of liquid to vapors is controlled by correlatingthe condition of time and pressure maintained on the heating andreaction elements with the temperature to which the particular oil isheated. It is desirable that the pressure should be such asto insure asubstantial proportion of the oil in the heating and reaction elementsremainingin the liqud state, thus preventing vaporization to dryness andthe conse-.

quent deposition of coke in the heating or reaction elements.

To illustrate, Mid-Continent 24 Baum gravity fuel oil when distilled todryness at atmospheric pressure, produces approximately 10% coke, whileon the other hand, if from the same oil only be distilled oil, theliquid residue remaining is free from objectionable amounts of A gas oiltreated in the same manner when distilled to dryness, leaves a residuecontaining about 2% coke, but when only about of same is distilled oil,"the liquid residue left is free from objectionable amountsof coke orsludge.

. In heating oils passing continuously through a pipe coil and reactionchamber the above holds true; thatis, iioil passing through the heatingcoil and reaction chamber. be wholly vaporized therein, coke will bedeposited approximately at that point where complete vaporization takesplace; Therefore, to avoid a deposition of coke in the heatingcoil andreaction chamber, it is temperature) as is necessary to hold a certainportion of the oil in the liquid state, including the higher boilingportion produced from the cracking.

when heating oil to cracking temperature and maintaining same under apressure there is no absolute rule that will enable one to predeterminethe exact pressure and temperatures-to be used, because at a givencracking temperature the proportion 0! oil vaporized according to thetime oil'is held at such temperature. Ii! in a' preliminary run ,coke befound in the heating coil or reaction chamber, then the pressure is toolow for the temperature employed, in which case the pressure must beincreased until a pressure is. reached that will prevent the depositionof coke in the tubes or reaction chamber. This always holds true,

essential to employ such pressure (relative to but if the temperatureschosen be so high that the corresponding reaction rate reaches a valuewhere it cannot be arrested quickly enough by partial cooling, then anundesirable portion of the oil undergoing treatment will be convertedinto fixedgas or coke.

By the use of high'temperatures the capacity of the cracking plantsisenormously increased, the anti-knock properties of the desired lowboiling products are greatly increased, and when producing a liquidresidue,-it will be substantially free from sludge and ocks, and willhave the desired viscosity.

In order to control these conditions the whole ofthe oil might beabruptly cooled and condensed, but this would be an uneconomicaloperation. It would necessitate the reheating of the treated oil,distilling off the gasoline and the intermediate fractions, the latterfor recracking, and leaving either coke or a liquid.

residue of the desired qualities. In this apparatus the heating, thecontrol of cracking, the separation of the vapors from the residue, theseparation of the lower boiling vapors from the higher boiling vapors,and the recracking of the latter, are all carried on simultaneously witha great saving of labor, fuel, and equipment.

It is of great importance that the degree of cooling of the heated massof oil be controlled. When making a liquid residue this is done in sucha way as to produce as liquid qnly the desired quality and quantity ofresidue. due is separated from the uncondensed portions and the latterseparated by condensing the heavier ends which with additional raw oilare subjected to repeated like heat treatments, meanwhile taking off thedesired low boiling products, condensing and withdrawing them from theapparatus.

It is readily seen that by this apparatus the oil can be heated to amuch higher temperature than heretofore possible with very beneficialresults at the same time avoiding the very serious difficulties andobjectionable reactions usually resulting from such high temperatures.

Attached is a schematic drawing of a side elevation of the apparatus.

Line marked I leads fromany suitable supply of oil to be treated. Bymeans of pump 2 the oil is forced through line 3, valve 4 being open!and valve 5 being closed. The oil is preferably discharged intodephlegmator 6 as shown; part or all of the oil may be fed direct.Dephlegmator 6 may be a combination of bubble trays'and perforated pans.The raw oil is fed onto the topof the perforated pans. These are used inthe lower section because when treating a heavy oil,

- such as crude fuel oil, topped crude, etc., in ordinary practice, ithas been found, if this oil befed onto bubble trays, it tends to more orless clog them; therefore, perforated pans may be used below the raw oilfeed point. When using gas oils or similar oils all trays may be of the)bubble plate type.

The oil may be preheated or put in at normal atmospheric temperatures.If the charging stock contains a substantial amount of the desired lowboiling products or water, it is of ad vantage to preheat it. As the oildescends through the perforated pans counter-current to the hotascending vapors, the latter are partially cooled causing the higherboiling point portions -to condense and work down to the bottom of thedephlegmator along with the raw oil fed in. By this action, the raw oilis substantially increased This resi'-' in temperature, and any water ordesired low boiling portions are vaporized and pass out of the top ofthe dephlegmator with the low boiling cracked vapors; The temperature ofthe oil accumulating in the bottom of the dephlegmator 6 5 oil, may bemanifolded, and the rest of the coil coil.

should be continuous, except in those plants where the capacity is sogreat as to permit manifolding the coils without reducing the velocityof 15 the oil to such an extent as to unduly prolong the time it isunder cracking temperatures. Openings should be provided in the coilsfor cleaning. In order to reduce the time factor, particularly in theheating element, without sub- 20 stantially changing the capacity, afluid of the I desired temperature may be injected in regulatedquantities, e. g., incondensible gas may be passed through line Hcontrolled by valve 9' into line H, or distillate may. be passed fromline 58 25 through line H controlled by valve 58' into line H. Valves53' and ID are control valves. Under certain conditions I may introducethe fluid at a point between the inlet and discharge of the heating coilto thus shorten the time ele- 30 ment from such point to the exit of theheating I have not shown this connection in the drawing, as those versedin the art will fully understand how to make such connection.

and reaction chamber H is controlled by valve 45' I6, which controls thedischarge of the oil into separating chamber l1. Here the vaporizedportion, governed by the degree of reduced pressure and substance usedfor cooling the heated mass, is separated from the unvaporized por- 50tion, the latter being withdrawn through line 18', controlled by valvel9, passed through cooling coil (not shown) and sent to storage.

The portion of the oil vaporized passes out of the top of separatingchamber l1, through'line 55 I8, into the lower section of dephlegmator6, valve 69 being opened and valve II being closed. (or the vapors maybe sent into spray 12, located below the liquid level, by closing valve89 and opening valve II having the vapors go through 0 line 10, or partmay be injected into dephlegmator 6 through spray I2 into the liquid andthe remainder injected above the liquid by the proper manipulation ofvalves 69 and ll) they are first boiling point, is cooled, condensed andpartially cooled by the incoming raw oil caus ng 65 That part 10 of thecoils functioning as a preheater for the ceiver I9, through line 20,through pump 2|, and

discharging it into line 22, valve 23 being opened and valve 24 beingclosed. This quantity of distillate is sprayed onto the top bubble platethrough spray 25. I

The remaining vapors from the top of dephlegmator 6 being of the desiredrange oi low boiling points, along with the uncondensable gas, passthrough line 26 and valve 26' through condensing coil 21, through line29, into receiver 19. The condensate is discharged through line 16.valve '86 controlling, to rundown tank (not shown). The condensateaccumulating in the bottom of dephlegmator '6 will contain more or.

less oil within the boiling range of the vapors going out of the top ofdephlegmator 6, these are recovered by what is termed reboilway toaccomplish this, by taking some of the uncondensable'gasfrom receiverl9, through line 30, valve 8| being open, and .by means or pump 3idischarging it through line 32 into coil 38, located in the uppersection of separating chamber ii. As this gas passes therethrough it isheated, then passes through line 84 into spray 95 located in the bottomoi. dephlegmator 6, thus acting as a reboiler.

It will be understood that other gases preheated in other ways may beused, as well as steam, which may be introduced through line 32,controlled by valve 32a. It should also be understood that instead oiheating the gases through coil 33 the raw oil being fed to the plant maybe heated in this matter. I have not shown the connections, because oneversed in the art will readily understand howto make these. In heatingthese gases or raw oil in coil 93 more or less of the higher boilingpoint vapors in separating chamber II will be condensed. These arecollected on nn 36 and automatically drain through line 91, controlledby valve 91', into the bottom section of dephlegmator 6.

If one wishes to make a liquid residue suitable for making asphalt, thenthe partial cooling of the oil should be done while the whole of the oilis under pressure, because pressure prevents vaporization of certainparts of the oil. It is desirable to reduce the temperature of this oilbelow the temperature at which these portions will vaporize whenthepressure is reduced. The degree of cooling will be governed. of course,by the quantity and quality ofresiduum desired.

Several methods of cooling are provided in this apparatus, the firstbeing, to take out of the bottom of the separating chamber '11 thenecessary ,volume oi oil through line 38, valve 69' being open, and topass it through cooler 40, which allows the cooling oil to be deliveredat any temperature desired. -The degree of cooling is important in somecases to avoid too great a shock cooling to the heated oil. From cooler40 the oil goes through line 4!, through pump 42, through line", valves44, 46, 46, 41, 48 and 49 being open, valves 59, 5!, 52, 53, 54, and 56being closed. In this'manner the cooled oil is, injected into spray 51,shown in the bottom section of reaction chamber l4. If a shorterreaction time be desired, then spray 51 may be located at such higherelevations in reaction chamber H as will bring this about.

Before the vaporized and unvaporiz ed oils pass from reaction chamber i4they are cooled under pressure to the desired degree. As they takenthrough line 20,

In the. attached drawing I-jbave shown one the amount taken oi! asvapors and the amount taken of! as liquid in separating chamber II. It

.will be understood that instead of taking ofl a part of the liquid fromseparating chamber l1, cooling it andinjecting it into reaction chamberM in the manner previously described, one can take the same oil from thestorage tank inwhich the residuum from the separating chamber is stored,and inject this directly into cooling sprayil. Another method ofbringing about this cooling is to' inject condensate from tank l9. Thatportion needed for cooling is through pump 2|, through valve 24, throughline, through valve '53, into line 43. In this case the valves alreadydescribed stay inv the same positions with the exception that valvesHand 44 are closed, valve 23 regulating the quantity going todephlegmator B. In using the condensate from receiver l9 for cooling theexit oil from the reaction chamber l4, such cooling material isvaporized by absorbing heat and this increases the volume of vapors inchamber l4, thus speeding up the discharge of the oil and reducing thetime of passage of the oil through the reaction chamber. In someoperations this is of great importance for obtaining gasoline with highanti-knock properties and producing a fuel oil of low viscosity free"from sludge.

Another method of cooling is to divert a part or all of the raw oilthrough line 59, valve 5' controlling the columns, valves 60, 59 and 49being open, valves 6|, 62, 48, 41, 46, 52, 45, 54, 44, 53 and 39 beingclosed.

When running this apparatus on fuel oil or topped crude and us a part ofit for cooling the oil in the reaction chamber l4, it must be borne inmind that part of such raw oil used for cooling which is not vaporizedat the temperature of this mixture will not be substantially brokendownin viscosity.

This is 01' great value where this residue is desired to produceasphalt. Where the residue is to be used for fuel, it then becomessomewhat of a detriment. Cooling of the oil in reaction chamber l4 maybe accomplished by using a ,part of the condensate from the bottom ofthe pressure has been released from this oil,

because on released pressure part of the unvaporized oil instantlyvaporize's and then is instantly. condensed by the injected cooling oil.This tends to further break down'the viscosity. However, if thetemperature of the oil is such as will cause it to completely vaporizeon release of pressure, the cooling must be brought about immediatelyand atthe point where the pressure is released, else coke will beformed. When the oil is at such .a high temperature that coke isdeposited under these conditions, then the cooling should be done beforethe pressure on the oil is released and in the manner already de-.scribed. The cooling of the oil, with any of the material previouslymentioned, afterthe pressure is released is accomplished by injectingthe cooling medium through line 64, valve 54 controlling, into line l5,either through valve 55 or 56,

and after the pressure has been released by con- :either before orafte'rthe pressure is released. In using steam before the pressure isreleased,

it is injected through line-65, valve 66 controlling. Steam is injectedinto the oil after the pressure is released through line 61, valve .68controlling.

Under certain conditions all of the oil passing from chamber H throughcontrol valve l6 will be vaporized in chamber l1 except the coke whichwill deposit on the bottom of the separating chamber I I. This is knownas a nonresiduumoperation and is brought about by the kind and degree ofpartial cooling of the whole of the oil leaving reaction chamber I 4. Assoon as the open portion of the lower section of separating chamber l1becomes filled with coke, the apparatus is shut down and such cokecleaned out. To avoid shutting down, a second separating chamber I! maybe provided so that the oil may be diverted into it while the firstchamber is being cleaned. Since this is well understood by'those versedin the art, I have not shown the arrangement on the drawing.

Suitable pyrometers and pressure gauges are provided while at L areliquid level gauges.

The vapors from the separating chamber may be injected into the liquidin the lower part of dephlegmator 6, .causing it to act as a reboiler.This is done by closing valve 69 and passing the vapors through line 10by opening valve II and discharging these vapors through spray l2.

. Provided one does not wish to provide a pump, the pressure held onreceiver [9 is such as to force the oil from'the receiver to the storagetank (not shown). This pressure is controlled by regulating thedischarge of uncondensable gas from the receiver through line 13,controlled by valve '14.

Illustrating the operation ofjthe apparatus, I give an example of onetype of operation using a 2i gravity topped crude from the Mid-Continentfield. As the oil flows through the heating elements located in thefurnace [2 it is quickly brought to a temperature of approximately 9'75degree F., and passes into the reaction chamber H, the whole of it beingmaintained at a pressure of approximately 375 pounds persquare inch andis subjected to this temperature for approximately one-sixth of oneminute. The whole of the oil continuously passes through'line l5 intoseparating chamber II, this chamber being held at approximately 30,pounds pressure, reduction of pressure from chamber I4 to chamber Ilbeing controlled by valve 16. In chamber l1, all of the volatile portionof the oil is vaporized and passes out through lines I! and .10 throughspray I2 into the bottom of the dephlegmator 6. Such amount of vaporscondensed in I! pass through line 31 and valve 31' into the bottom ofdephlegmator 6. The coke accumulates in chamber l1. As the vapors passup through the dephlegmator 6, they arecooled, by either raw oil and/orother means already described. The

- final vapors-exiting from the top of dephlegmator 8 through line Hinto heating oils in furnace l2.

If, instead of producing coke, it is desired to produce a liquidresidue, then the heated oil in chamber II is reduced in temperature bythe injection through spray 61 of the desired kind and quantity ofcooling oil so as to bring the heated mass down in temperature so thatwhen it is discharged into chamber I! at a reduced pressure, it willleave a liquid residue of the desired quality and quantity in chamber H,which is continuously withdrawn through line 18', controlled by valve l9and passed through a cooling oil and to storage tanks (not shown).

I claim as my invention:

1. An oil cracking apparatus comprising oil heating means and a reactionchamber in communication therewith, a vapor separating chamher, atransfer line for passing oil constituents from said reaction chamber tosaid separating chamber, means for condensing the vapors separated insaid separating chamber, means for passing unvaporized oil from theseparating chamber into the reaction chamber, and a direct communicationbetween the condensing means and the transfer line for introducing tosaid transfer line a portion of the condensate formed in said condensingmeans.

2. An oil cracking apparatus comprising oil heating means and a reactionchamber in com munication therewith, a vapor separating chamber, atransfer line for passing oil constituents from said reaction chamber tosaid separating chamber, means for passing unvaporized oil from theseparating chamber into the reaction chamber, a dephlegmator and a finalcondenser serially connected to said separating chamber, and a directcommunication between the final con- CARBON P. DUBBS.

